A two-hour movie, projected at 24 frames per second, comprises almost 175,000 stills. But according to French director Céline Sciamma, whose new film Portrait of a Lady on Fire has been wowing audiences at festivals around the world, it’s really just a handful of pictures that drive the motion picture.

“You have about five or six images that you really want to make,” she says. “They show you the path … and they make you brave.”

For Sciamma, one of those was the image of the woman played by Adèle Haenel, her dress licked by a flame at ground level while she gazes at the camera, unconcerned or perhaps unaware. So, too, was another startling shot, of a woman running headlong toward a seaside cliff top, seemingly bent on self-destruction.

A still from Portrait of a Lady on Fire.Courtesy of TIFF

And then the delicious final scene, which I promised her I won’t write about, for fear of spoiling the journey. “That was my first idea,” says the writer/director. “That’s why I made this film.”

Portrait of a Lady on Fire won the Queer Palm (an independently sponsored prize for selected LGBT-relevant films) and the Best Screenplay prize at Cannes, the People’s Choice Award at the Melbourne International Film Festival and the Film Critics Awards in Norway. This week, it had its North American premiere in Toronto. It tells the story of Héloïse (Haenel), an 18th-century noblewoman in Brittany soon to be married off to a stranger in Milan.

Before the nuptials can take place, the groom wants a portrait of his future wife. But the stubborn Héloïse has already sent one painter packing. So her mother arranges for another, Marianne (Noémie Merlant), to stay with them. She will pose as a companion, secretly observing her subject by day and then committing her to canvas at night.

Sciamma says the notion of the painter-in-disguise – such a powerful hook for a would-be viewer – came to her late in the writing stage. “Something was missing,” she says. “I had to dream a little bit longer.”

But that image of a woman ablaze was so vital to the film that the scene around it became the focal point of the movie, aurally as well as visually. Sciamma says she “wanted to invoke all the tools of cinema” to make it.

To that end, she worked with her composer to create a piece of music that could be sung in a round by a group of women who have gathered outside. It’s a powerful moment in the movie; the soundtrack, which has previously been the domain of quiet domestic noises like the crackle of a fire, slowly builds into a joyous, polyphonic, polyrhythmic cacophony.

“I really wanted the film to invent its own language and its own grammar,” says Sciamma of the scene and the song. “It becomes an anthem for the film and … maybe it will become an anthem for something else.”

Casting about for another way to put this into words, she references an American poet who died this year: “Mary Oliver says that a broken heart is a heart that is open to the world.” When I look up the exact quotation, it reads: “I tell you this / to break your heart / by which I mean only / that it break open and never close again / to the rest of the world.” Sciamma’s story does that, and more.